A decrease in size and an increase in output power are required for electric car and hybrid car motors. An improvement in the performances is expected by using a multiple-winding coil, in which a plurality of coils of one phase is formed from one coil raw wire, in order to suppress an increase of the electric resistance associated with the wire connection process between coils. The conventional techniques for the multiple-winding coil manufacturing method and manufacturing apparatus are disclosed in Patent Literature 1, Patent Literature 2, and Patent Literature 3.
Patent Literature 1 discloses the techniques about a coil, a slotless-motor, and a method for manufacturing the coil.
Specifically, there is disclosed a coil manufacturing method comprising the steps of: using a bending machine including a fixture for fixing a conducting wire and a press tool for pressing a conducting wire in a direction perpendicular thereto; causing a conducting wire, which is a raw material, to protrude by a predetermined length and fixing the base thereof with the fixture, and in this state, pressing a protruding portion of the conducting wire in a direction perpendicular thereto on a flat plane with the press tool and bending this conducting wire at a right angle; and after the above-described steps, sequentially repeating the operations to cause the conducting wire to protrude by a predetermined length from the fixture and bend the same at a right angle, thereby forming a spiral body having a square shape.
Patent Literature 2 discloses a technique about the method for manufacturing a salient pole concentrated-winding stator of an electric motor.
Specifically, there is disclosed a method for manufacturing a stator, the method comprising the step of arranging three-phases of coil groups 18 including a plurality of coils 13 around each of which the same winding wire 14 is wound via a jumper part 14T and which are arranged stepwise so that their height levels gradually decrease from a first layer L1 to an n-th layer Ln, so that the arrangement orders of three phases in each layer are coincident with one another, the method further comprising the step of inserting the coil group into a teeth 11b of a stator core 11 while aligning all the coils 13 in line by repeating, until all the coils are brought to the same level, a work to displace the coil, while bypassing the jumper part 14T for another phase, so as to bring its height to the same height as a reference layer, in the order from the coil 13 closer to the reference layer which is either one of the layers.
Patent Literature 3 discloses a method for manufacturing a concentrated-winding stator and the technique about this manufacturing method.
Specifically, there is disclosed a method for manufacturing a coil, the method comprising the steps of: forming a coil unit by continuously forming a plurality of concentrated-winding parts with the same conductive wire; rotating the coil unit of a predetermined phase once for each concentrated-winding part of the coil unit of another phase and arranging the concentrated-winding part of the coil unit of the predetermined phase in the concentrated-winding part of the coil unit of the other phase; by repeating the above-described steps, aligning the concentrated-winding part of the coil unit of each phase in accordance with an arrangement order with respect to a stator; and fitting a teeth part of the stator into the concentrated-winding parts of the coil unit group which is formed by aligning and arranging the coil units of all phases.